Alkyl levulinates as `green chemistry' precursors: butane-1,4-diyl bis­(4-oxo­pentan­oate) and hexane-1,6-diyl bis­(4-oxo­pentan­oate)

Levulinic acid derivatives are potential `green chemistry' renewably sourced mol­ecules with utility in industrial coatings applications. Suitable single crystals of the centrosymmetric title compounds, C₁₄H₂₂O₆ and C₁₆H₂₆O₆, respectively, were obtained with difficulty. The data for the latter hexane-1,6-diyl compound were extracted from the major fragment of a three-component twinned crystal. Both compounds crystallize in similar-sized unit cells with identical symmetry, utilizing the same weak nonconventional attractive C-H...O(ketone) hydrogen bonds via C(4) and C(5) motifs, which expand to R²₂(30) ring and C²₂(14) chain motifs. Their different packing orientations in similar-sized unit cells suggest that crystal growth involving packing mixes could lead to inter­growths or twins.

S1. Comment

Levulinic acid is readily derived from depolymerized carbohydrate biomass (Corma et al., 2007), either directly (Hayes et al., 2005) or as an alkyl ester (Wu et al., 2012; Tominaga et al., 2011), and is considered a potential renewable platform chemical. Our interest in this compound stems from its applications as a renewable and versatile ingredient suitable for coatings applications. Levulinic acid itself is often a low-viscosity liquid at room temperature, crystallizing spontaneously with a recorded melting point of 303–306 K.

For utility in commodity coatings applications, these compounds must be readily synthesized, generally in a `one-pot' process, to have a cost-effective and competitive advantage over existing dispersants and plasticizers. In the process of generating a series of readily synthesized waxy hydrophobic but water-dispersible levulinyl species, we observed that 1,4-dilevulinylbutanoate [butane-1,4-diyl bis(4-oxopentanoate), (I)] and 1,6-dilevulinylhexanoate [hexane-1,6-diyl bis(4-oxopentanoate), (II)] form crystalline species. Other derivatives, such as the per-levulinates of 1,4-butenoate, ethylene glycol and propylene glycol, are all low-viscosity oils at room temperature, while the longer alkyl chain 1,9-nonadiol derivative is a waxy partially crystalline solid. Our interest was piqued as to the conformation and packing of these simple molecules, with a view to understanding their role and structure in de novo film-forming components, as well as their likely interaction with larger polymers, particularly in the role of lowering glass transition temperatures (T_g).

Fischer esterification of polyols in the presence of a 1.2 molar excess of levulinic acid and catalytic acid (with or without additional solvent) at elevated temperature and reduced pressure rapidly generated compounds (I) and (II). Recrystallization was readily effected from a number of organic solvents, with an ethanol–water solution [Solvent ratio?] affording white [Colourless in CIF tables - please clarify] plates.

Both (I) and (II) crystallize with one independent centrosymmetric molecule in the asymmetric unit (Figs. 1 and 2). Both of them, and related compounds that were also prepared, are prone to form intergrown and twinned crystals. In this case we were able to locate a suitable single crystal for the butane derivative, (I), which is the only crystal structure of this series successfully solved and refined to date. Data for the hexane derivative, (II), were obtained by extraction from a multiple-fragment crystal via CrysAlis PRO (Oxford Diffraction, 2007), where the data were processed as a twin containing three components, but only data from the most intense component were used (estimated as 56% of the fragment).

There are no unusual bond lengths or angles in the structures of (I) and (II), and similar conformation angles are observed along the atom chains (Table 1). There are no closely related structures in the Cambridge Structural Database (CSD, Version?; Allen, 2002), the closest being 3-acetyl-4-oxopentanoic acid (CSD refcode ICUBUF; Ferrari et al., 2011), which is consistent with the difficulty in obtaining adequate single crystals and the observed weak intermolecular bonding.

The dimer molecule packing is consistent across both structures, being parallel strands crosslinked by weak non-conventional C—H···O(ketone) hydrogen bonds (Figs. 3 and 4), and with only van der Waal contacts between the capping methyl groups. The commonality of the binding is shown in a motif analysis, with the C—H···O(ketone) interactions (Tables 2 and 3) giving rise to R²₂(30) ring and C²₂(14) chain motifs (Bernstein et al., 1995). These are probably supplemented by even weaker C—H···O(ether) interactions.

In terms of the disposition of the chain of linked aliphatic atoms, a similar cell packing is noted in butane-1,4-diyl bis(chloroacetate) (MAJRAR; Urpí et al., 2004), where C—H···O(ketone) is the only attractive interaction, although probably stronger, with a C—H···O angle of 160° and H···O = 2.55 Å. However, the dimer-type packing (here) is not reproduced, with a different R⁴₄(30) motif observed. By contrast, in ICUBUF a conventional O—H···O hydrogen bond links the molecules (H···O = 1.84 Å), supplemented by two C—H···O(ketone) interactions, with H···O = 2.55 and 2.48 Å.

Although the cell dimensions of (I) and (II) are closely related in magnitude with identical space groups, the alignments of the dimer units, approximately perpendicular to the b axis, are significantly different. In (I), the molecules are aligned parallel to the (101) crystallographic planes, while in (II) the alignment is ~72° different, being parallel to the (201) plane (Figs. 3 and 4). This observation also suggests why these compounds might tend to form intergrown or twinned crystals: the `misalignment' of the molecules could permit differently oriented domains to combine, thereby creating such imperfect (single) crystals.

Related literature

For related literature, see: Allen (2002); Bernstein et al. (1995); Corma et al. (2007); Ferrari et al. (2011); Hayes et al. (2005); Oxford (2007); Sheldrick (2008); Tominaga et al. (2011); Urpí et al. (2004); Wu et al. (2012).

S2. Experimental

For the preparation of both compounds, the general procedure was as follows. The relevant diol (~2 g) was added to levulinic acid (2.1 equivalents), toluene (50 ml) and p-toluene sulfonic acid (5 mg), and the mixture heated to reflux under Dean–Stark conditions. After 12–16 h, the reaction mixture was cooled and evaporated to dryness and crystalline material was readily prepared from the solid using a variety of solvents. Crystals produced from an ethanol–water solution [Solvent ratio?] provided the best defined examples. [Abstract states that crystals were only obtained with difficulty, and here states `readily' - please clarify]

Analysis for (I), 1,4-dilevulinylbutanoate: m.p. 318–323 K (differential scanning calorimetry); ¹H NMR (500 MHz, CDCl₃, δ, p.p.m.): 1.67 (m, 4H, H2'), 2.17 (s, 6H, H1), 2.55 (t, J = 6.7 Hz, 4H, H4), 2.73 (t, J = 6.7 Hz, 4H, H3), 4.07 (m, 4H, H1'); ¹³C NMR (125 MHz, CDCl₃, δ, p.p.m.): 25.3 (t, C2'), 28.0 (t, C4), 29.8 (q, C1), 37.9 (t, C3), 64.1 (t, C1'), 172.7 (s, C5), 206.6 (s, C2); time-of-flight HRMS, found: 309.1313; calculated for [C₁₄H₂₂O₆Na]⁺: 309.1314.

Analysis for (II), 1,6-dilevulinylhexanoate: m.p. 321–324 K (differential scanning calorimetry); ¹H NMR (500 MHz, CDCl₃, δ, p.p.m.): 1.36 (m, 4H, H3'), 1.61 (m, 4H, H2'), 2.18 (s, 6H, H1), 2.56 (t, J = 6.7 Hz, 4H, H4), 2.73 (t, J = 6.7 Hz, 4H, H3), 4.05 (t, J = 6.7 Hz, 4H, H1'); ¹³C NMR (125 MHz, CDCl₃, δ, p.p.m.): 25.3 (t, C3'), 28.0 (t, C4), 28.5 (t, C2'), 29.9 (q, C1), 38.0 (t, C3), 64.6 (t, C1'), 172.8 (s, C5), 206.6 (s, C2); time-of-flight HRMS, found: 337.1628; calculated for [C₁₆H₂₆O₆Na]⁺: 337.1627.

S3. Refinement

The data for (II) were processed as three twin components, with the final data extracted from the major component (56% of the total); the twin law matrix used was 1.0173 -0.0359 0.0668/0.0072 0.9985 0.0179/-0.0378 -0.0712 0.9829 (CrysAlisPro; Oxford Diffraction, 2007). A further 11 reflections were identified as subject to overlap of data, with Δ(F_o² - Fc²)/σ(F_o²) > 9, and they were omitted from the refinement using the OMIT command in SHELXL2012 (Sheldrick, 2008).

All methyl H atoms were constrained to an ideal geometry, with C—H = 0.98 Å and U_iso(H) = 1.5U_eq(C), but they were allowed to rotate freely about the adjacent C—C bond. All other C bound H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H = 0.99 Å and U_iso(H) = 1.2U_eq(C).

Computing details

For both compounds, data collection: CrysAlis PRO (Oxford Diffraction, 2007); cell refinement: CrysAlis PRO (Oxford Diffraction, 2007); data reduction: CrysAlis PRO (Oxford Diffraction, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL2012 (Sheldrick, 2008); molecular graphics: ORTEP in WinGX (Farrugia, 2012) and Mercury (Macrae et al., 2008); software used to prepare material for publication: SHELXL2012 (Sheldrick, 2008) and PLATON (Spek, 2009).

Figures

	Fig. 1. A view of the molecule of (I), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 35% probability level. Unique atoms are labelled; the centre of symmetry is midway between atoms C7 and C7^i. [Symmetry code: (i) -x+1, -y+1, -z+1.]
	Fig. 2. A view of the molecule of (II), with the atom-numbering scheme. Displacement ellipsoids are drawn at the 35% probability level. Unique atoms are labelled; the centre of symmetry is midway between atoms C8 and C8^i. [Symmetry code: (i) -x+1, -y+1, -z+1.]
	Fig. 3. The cell contents of (I), viewed approximately down the bc diagonal. Atoms involved in contacts are shown as balls. Intermolecular binding contacts are shown as dashed lines. [Symmetry codes: (i) x, -y+3/2, -z+1/2; (ii) x, -y+1/2, z-1/2; (iii) -x+1, -y+1, -z+1; (iv) -x+1, y-1/2, -z+3/2; (v) -x+1, y-1/2, -z+1/2.]
	Fig. 4. The cell contents of (II), viewed approximtely down the bc diagonal. Atoms involved in contacts are shown as balls. Intermolecular binding contacts are shown as dashed lines. [Symmetry codes: (i) x, -y+1/2, z-1/2; (ii) x, -y+3/2, z-1/2; (iii) x, -y+1/2, z+1/2.]

(I) Butane-1,4-diyl bis(4-oxopentanoate)

Crystal data

C14H22O6	F(000) = 308
Mr = 286.32	Dx = 1.283 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54178 Å
a = 13.4857 (4) Å	Cell parameters from 4250 reflections
b = 5.0971 (1) Å	θ = 3.5–73.6°
c = 11.5521 (3) Å	µ = 0.84 mm^−1
β = 111.018 (3)°	T = 120 K
V = 741.24 (3) Å^3	Plate, colourless
Z = 2	0.15 × 0.15 × 0.02 mm

Data collection

Oxford SuperNova Dual diffractometer (Cu at zero) with Atlas detector	1486 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	1306 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.029
Detector resolution: 10.6501 pixels mm^-1	θmax = 73.8°, θmin = 3.5°
ω scans	h = −16→16
Absorption correction: multi-scan CrysAlis PRO (Oxford Diffraction, 2007)	k = −6→5
Tmin = 0.736, Tmax = 1.000	l = −13→14
7678 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.035	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.094	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0471P)^2 + 0.2444P] where P = (Fo^2 + 2Fc^2)/3
1486 reflections	(Δ/σ)max < 0.001
92 parameters	Δρmax = 0.20 e Å^−3
0 restraints	Δρmin = −0.21 e Å^−3

Special details

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.08563 (7)	0.73563 (17)	0.71532 (8)	0.0259 (2)
O2	0.34329 (7)	0.64091 (19)	0.78649 (9)	0.0309 (3)
O3	0.33826 (7)	0.39634 (17)	0.62288 (8)	0.0234 (2)
C1	0.10244 (10)	0.7000 (3)	0.92727 (12)	0.0270 (3)
H1A	0.0545	0.8515	0.9081	0.040*
H1B	0.1709	0.7498	0.9898	0.040*
H1C	0.0712	0.5569	0.9594	0.040*
C2	0.11893 (9)	0.6109 (2)	0.81135 (11)	0.0197 (3)
C3	0.17633 (9)	0.3543 (2)	0.82110 (11)	0.0220 (3)
H3A	0.1288	0.2110	0.8269	0.026*
H3B	0.2392	0.3541	0.8990	0.026*
C4	0.21293 (9)	0.2958 (2)	0.71380 (11)	0.0219 (3)
H4A	0.2345	0.1093	0.7178	0.026*
H4B	0.1527	0.3226	0.6348	0.026*
C5	0.30429 (9)	0.4655 (2)	0.71474 (11)	0.0204 (3)
C6	0.42676 (9)	0.5460 (2)	0.61330 (11)	0.0236 (3)
H6A	0.4891	0.5330	0.6914	0.028*
H6B	0.4070	0.7332	0.5972	0.028*
C7	0.45242 (9)	0.4308 (2)	0.50719 (11)	0.0215 (3)
H7A	0.3900	0.4487	0.4295	0.026*
H7B	0.4683	0.2416	0.5224	0.026*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0292 (5)	0.0241 (5)	0.0268 (5)	0.0025 (4)	0.0130 (4)	0.0047 (4)
O2	0.0304 (5)	0.0327 (5)	0.0352 (5)	−0.0107 (4)	0.0187 (4)	−0.0123 (4)
O3	0.0226 (4)	0.0260 (5)	0.0271 (5)	−0.0068 (3)	0.0154 (4)	−0.0044 (3)
C1	0.0312 (7)	0.0262 (7)	0.0269 (7)	0.0022 (5)	0.0146 (5)	−0.0004 (5)
C2	0.0166 (5)	0.0205 (6)	0.0241 (6)	−0.0042 (4)	0.0098 (5)	0.0003 (5)
C3	0.0221 (6)	0.0211 (6)	0.0268 (6)	0.0007 (5)	0.0135 (5)	0.0032 (5)
C4	0.0217 (6)	0.0200 (6)	0.0277 (6)	−0.0018 (5)	0.0136 (5)	−0.0017 (5)
C5	0.0195 (6)	0.0205 (6)	0.0235 (6)	0.0015 (5)	0.0103 (4)	0.0008 (5)
C6	0.0208 (6)	0.0248 (6)	0.0291 (6)	−0.0064 (5)	0.0137 (5)	−0.0020 (5)
C7	0.0195 (6)	0.0236 (6)	0.0236 (6)	−0.0022 (5)	0.0104 (5)	0.0002 (5)

Geometric parameters (Å, º)

O1—C2	1.2162 (14)	C3—H3B	0.9900
O2—C5	1.2042 (15)	C4—C5	1.5023 (16)
O3—C5	1.3450 (14)	C4—H4A	0.9900
O3—C6	1.4537 (14)	C4—H4B	0.9900
C1—C2	1.5043 (16)	C6—C7	1.5071 (16)
C1—H1A	0.9800	C6—H6A	0.9900
C1—H1B	0.9800	C6—H6B	0.9900
C1—H1C	0.9800	C7—C7^i	1.525 (2)
C2—C3	1.5034 (16)	C7—H7A	0.9900
C3—C4	1.5191 (16)	C7—H7B	0.9900
C3—H3A	0.9900
C5—O3—C6	116.34 (9)	C5—C4—H4B	109.0
C2—C1—H1A	109.5	C3—C4—H4B	109.0
C2—C1—H1B	109.5	H4A—C4—H4B	107.8
H1A—C1—H1B	109.5	O2—C5—O3	123.33 (11)
C2—C1—H1C	109.5	O2—C5—C4	125.95 (11)
H1A—C1—H1C	109.5	O3—C5—C4	110.72 (10)
H1B—C1—H1C	109.5	O3—C6—C7	106.96 (9)
O1—C2—C3	122.34 (11)	O3—C6—H6A	110.3
O1—C2—C1	122.01 (11)	C7—C6—H6A	110.3
C3—C2—C1	115.63 (10)	O3—C6—H6B	110.3
C2—C3—C4	114.77 (10)	C7—C6—H6B	110.3
C2—C3—H3A	108.6	H6A—C6—H6B	108.6
C4—C3—H3A	108.6	C6—C7—C7^i	110.86 (12)
C2—C3—H3B	108.6	C6—C7—H7A	109.5
C4—C3—H3B	108.6	C7^i—C7—H7A	109.5
H3A—C3—H3B	107.6	C6—C7—H7B	109.5
C5—C4—C3	112.75 (10)	C7^i—C7—H7B	109.5
C5—C4—H4A	109.0	H7A—C7—H7B	108.1
C3—C4—H4A	109.0
O1—C2—C3—C4	14.14 (16)	C3—C4—C5—O2	−3.89 (18)
C1—C2—C3—C4	−167.57 (10)	C3—C4—C5—O3	176.22 (10)
C2—C3—C4—C5	71.65 (13)	C5—O3—C6—C7	178.66 (10)
C6—O3—C5—O2	0.07 (17)	O3—C6—C7—C7^i	−177.88 (12)
C6—O3—C5—C4	179.96 (10)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···O2^ii	0.99	2.60	3.2771 (15)	126
C3—H3A···O1^iii	0.99	2.71	3.4440 (14)	131

Symmetry codes: (ii) x, −y+3/2, z−1/2; (iii) x, y−1, z.

(II) hexane-1,6-diyl bis(4-oxopentanoate)

Crystal data

C16H26O6	F(000) = 340
Mr = 314.36	Dx = 1.259 Mg m^−3
Monoclinic, P21/c	Cu Kα radiation, λ = 1.54178 Å
a = 14.9937 (7) Å	Cell parameters from 1410 reflections
b = 5.0837 (2) Å	θ = 3.1–73.7°
c = 11.4485 (5) Å	µ = 0.79 mm^−1
β = 108.110 (5)°	T = 120 K
V = 829.41 (7) Å^3	Plate, colourless
Z = 2	0.18 × 0.15 × 0.04 mm

Data collection

Oxford SuperNova Dual diffractometer (Cu at zero) with Atlas detector	1630 independent reflections
Radiation source: SuperNova (Cu) X-ray Source	1151 reflections with I > 2σ(I)
Mirror monochromator	Rint = 0.120
Detector resolution: 10.6501 pixels mm^-1	θmax = 73.9°, θmin = 3.1°
ω scans	h = −18→18
Absorption correction: multi-scan CrysAlis PRO (Oxford Diffraction, 2007)	k = −6→5
Tmin = 0.731, Tmax = 1.000	l = −13→13
5571 measured reflections

Refinement

Refinement on F^2	0 restraints
Least-squares matrix: full	Hydrogen site location: inferred from neighbouring sites
R[F^2 > 2σ(F^2)] = 0.056	H-atom parameters constrained
wR(F^2) = 0.159	w = 1/[σ^2(Fo^2) + (0.0696P)^2 + 0.3109P] where P = (Fo^2 + 2Fc^2)/3
S = 1.03	(Δ/σ)max < 0.001
1630 reflections	Δρmax = 0.24 e Å^−3
101 parameters	Δρmin = −0.26 e Å^−3

Special details

Experimental. Dimensions are approximate from (poor)photo taken.

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Ų)

	x	y	z	Uiso*/Ueq
O1	0.07634 (12)	0.2648 (3)	−0.14788 (14)	0.0345 (4)
O2	0.30379 (12)	0.3561 (4)	−0.02015 (14)	0.0396 (5)
O3	0.29921 (11)	0.5990 (3)	0.14100 (13)	0.0320 (4)
C1	0.08998 (18)	0.2990 (5)	−0.3488 (2)	0.0356 (6)
H1A	0.1500	0.2423	−0.3579	0.053*
H1B	0.0645	0.4445	−0.4056	0.053*
H1C	0.0457	0.1516	−0.3677	0.053*
C2	0.10501 (15)	0.3890 (5)	−0.21895 (19)	0.0287 (5)
C3	0.15670 (16)	0.6447 (5)	−0.18450 (19)	0.0310 (5)
H3A	0.1152	0.7894	−0.2274	0.037*
H3B	0.2120	0.6426	−0.2143	0.037*
C4	0.18958 (16)	0.7030 (5)	−0.04804 (19)	0.0306 (5)
H4A	0.2095	0.8893	−0.0352	0.037*
H4B	0.1365	0.6782	−0.0150	0.037*
C5	0.26942 (15)	0.5306 (5)	0.02171 (19)	0.0295 (5)
C6	0.37718 (16)	0.4486 (5)	0.22005 (19)	0.0326 (5)
H6A	0.4311	0.4532	0.1876	0.039*
H6B	0.3585	0.2630	0.2243	0.039*
C7	0.40336 (15)	0.5727 (5)	0.34523 (19)	0.0304 (5)
H7A	0.3492	0.5621	0.3771	0.036*
H7B	0.4177	0.7610	0.3382	0.036*
C8	0.48793 (15)	0.4399 (5)	0.43627 (18)	0.0304 (5)
H8A	0.4744	0.2504	0.4412	0.036*
H8B	0.5427	0.4559	0.4059	0.036*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
O1	0.0442 (9)	0.0317 (9)	0.0299 (8)	−0.0032 (7)	0.0149 (7)	0.0044 (6)
O2	0.0438 (10)	0.0419 (11)	0.0312 (9)	0.0111 (8)	0.0089 (7)	−0.0055 (7)
O3	0.0358 (8)	0.0362 (9)	0.0226 (8)	0.0076 (7)	0.0069 (6)	−0.0008 (6)
C1	0.0445 (13)	0.0339 (13)	0.0300 (12)	−0.0028 (10)	0.0139 (10)	−0.0026 (9)
C2	0.0298 (11)	0.0300 (12)	0.0260 (11)	0.0037 (8)	0.0085 (9)	0.0025 (8)
C3	0.0353 (12)	0.0297 (12)	0.0277 (11)	−0.0009 (9)	0.0096 (9)	0.0028 (8)
C4	0.0362 (12)	0.0280 (12)	0.0270 (11)	0.0008 (9)	0.0090 (9)	0.0007 (8)
C5	0.0330 (11)	0.0299 (12)	0.0260 (10)	−0.0025 (9)	0.0095 (9)	0.0003 (9)
C6	0.0327 (11)	0.0354 (13)	0.0277 (11)	0.0069 (10)	0.0065 (9)	0.0019 (9)
C7	0.0324 (11)	0.0328 (12)	0.0267 (11)	0.0011 (9)	0.0102 (9)	0.0026 (9)
C8	0.0308 (11)	0.0320 (12)	0.0281 (11)	0.0008 (9)	0.0089 (9)	0.0016 (9)

Geometric parameters (Å, º)

O1—C2	1.209 (3)	C4—C5	1.498 (3)
O2—C5	1.198 (3)	C4—H4A	0.9900
O3—C5	1.344 (3)	C4—H4B	0.9900
O3—C6	1.454 (3)	C6—C7	1.502 (3)
C1—C2	1.504 (3)	C6—H6A	0.9900
C1—H1A	0.9800	C6—H6B	0.9900
C1—H1B	0.9800	C7—C8	1.526 (3)
C1—H1C	0.9800	C7—H7A	0.9900
C2—C3	1.502 (3)	C7—H7B	0.9900
C3—C4	1.514 (3)	C8—C8^i	1.518 (4)
C3—H3A	0.9900	C8—H8A	0.9900
C3—H3B	0.9900	C8—H8B	0.9900
C5—O3—C6	116.44 (18)	O2—C5—O3	123.3 (2)
C2—C1—H1A	109.5	O2—C5—C4	126.3 (2)
C2—C1—H1B	109.5	O3—C5—C4	110.38 (19)
H1A—C1—H1B	109.5	O3—C6—C7	107.10 (18)
C2—C1—H1C	109.5	O3—C6—H6A	110.3
H1A—C1—H1C	109.5	C7—C6—H6A	110.3
H1B—C1—H1C	109.5	O3—C6—H6B	110.3
O1—C2—C3	122.5 (2)	C7—C6—H6B	110.3
O1—C2—C1	122.1 (2)	H6A—C6—H6B	108.5
C3—C2—C1	115.42 (19)	C6—C7—C8	112.41 (19)
C2—C3—C4	114.59 (18)	C6—C7—H7A	109.1
C2—C3—H3A	108.6	C8—C7—H7A	109.1
C4—C3—H3A	108.6	C6—C7—H7B	109.1
C2—C3—H3B	108.6	C8—C7—H7B	109.1
C4—C3—H3B	108.6	H7A—C7—H7B	107.9
H3A—C3—H3B	107.6	C8^i—C8—C7	112.2 (2)
C5—C4—C3	112.67 (19)	C8^i—C8—H8A	109.2
C5—C4—H4A	109.1	C7—C8—H8A	109.2
C3—C4—H4A	109.1	C8^i—C8—H8B	109.2
C5—C4—H4B	109.1	C7—C8—H8B	109.2
C3—C4—H4B	109.1	H8A—C8—H8B	107.9
H4A—C4—H4B	107.8
O1—C2—C3—C4	13.4 (3)	C3—C4—C5—O2	−2.8 (3)
C1—C2—C3—C4	−167.4 (2)	C3—C4—C5—O3	176.76 (19)
C2—C3—C4—C5	71.6 (3)	C5—O3—C6—C7	175.38 (19)
C6—O3—C5—O2	0.0 (3)	O3—C6—C7—C8	−177.39 (18)
C6—O3—C5—C4	−179.66 (19)	C6—C7—C8—C8^i	−178.1 (2)

Symmetry code: (i) −x+1, −y+1, −z+1.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C7—H7A···O2^ii	0.99	2.62	3.284 (3)	125
C3—H3A···O1^iii	0.99	2.71	3.447 (3)	132

Symmetry codes: (ii) x, −y+1/2, z+1/2; (iii) x, y+1, z.